The Amblystegiaceae contain ca. 30 genera and 120-170 species (Hedenäs, 2003), in large part associated with the Northern Hemisphere. For the Neotropics 20 genera and 43 species are recorded (Hedenäs, 2003). In Bolivia 12 genera and 20 species are recognized. Many of the species are commonly found in wet sites, often in bogs and seeps, margin of lakes and ponds, or along streams and rivers, at mostly high elevations. Generalizations often associated with the Amblystegiaceae include wet habitats such as marshes and bogs, leaf texture mostly smooth (rarely plicate), costa variable in a single plant or not (single, forked or absent), alar cells undifferentiated or if differentiated then enlarged and oblong, or if quadrate then cells few and small, usually firm- or thick-walled, capsules typically horizontal, strongly asymmetric and curved, exostome teeth yellow-brown. The Amblystegiaceae has been circumscribed and reclassified several times in recent years. The latest classification would recognize the family Calliergonaceae, composed of five genera, two represented in Bolivia: Straminergon, Warnstorfia. The family has been revised for the Neotropics by Hedenäs (2003). This treatment is largely adapted from Hedenäs (2003), including the taxonomic concepts.

17. Stem leaf costa single and long, or double and short in some leaves; alar cells forming a travnsverse-triangular group, extending from leaf margin to full or 2/3 distance toward the double costa … Drepanocladus (D. polygamus)